/* Microsoft Reference Implementation for TPM 2.0
 *
 *  The copyright in this software is being made available under the BSD License,
 *  included below. This software may be subject to other third party and
 *  contributor rights, including patent rights, and no such rights are granted
 *  under this license.
 *
 *  Copyright (c) Microsoft Corporation
 *
 *  All rights reserved.
 *
 *  BSD License
 *
 *  Redistribution and use in source and binary forms, with or without modification,
 *  are permitted provided that the following conditions are met:
 *
 *  Redistributions of source code must retain the above copyright notice, this list
 *  of conditions and the following disclaimer.
 *
 *  Redistributions in binary form must reproduce the above copyright notice, this
 *  list of conditions and the following disclaimer in the documentation and/or
 *  other materials provided with the distribution.
 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ""AS IS""
 *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
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 */
#include "Tpm.h"
#include "VerifySignature_fp.h"

#if CC_VerifySignature  // Conditional expansion of this file

/*(See part 3 specification)
// This command uses loaded key to validate an asymmetric signature on a message
// with the message digest passed to the TPM.
*/
//  Return Type: TPM_RC
//      TPM_RC_ATTRIBUTES         'keyHandle' does not reference a signing key
//      TPM_RC_SIGNATURE          signature is not genuine
//      TPM_RC_SCHEME             CryptValidateSignature()
//      TPM_RC_HANDLE             the input handle is references an HMAC key but
//                                the private portion is not loaded
/*
This command uses loaded keys to validate a signature on a message with the message digest passed to the TPM.
If the signature check succeeds, then the TPM will produce a TPMT_TK_VERIFIED. Otherwise, the TPM shall return TPM_RC_SIGNATURE.
If the key is in the NULL hierarchy, then digest in the ticket will be the Empty Buffer.
NOTE 1 A valid ticket may be used in subsequent commands to provide proof to the TPM that the TPM has
validated the signature over the message using the key referenced by keyHandle.
If keyHandle references an asymmetric key, only the public portion of the key needs to be loaded. 
If keyHandle references a symmetric key, both the public and private portions need to be loaded.
NOTE 2 The sensitive area of the symmetric object is required to allow verification of the symmetric signature (the HMAC).
此命令使用加载的密钥来验证消息上的签名以及传递给 TPM 的消息摘要。
如果签名检查成功，则 TPM 将生成 TPMT_TK_VERIFIED。 否则，TPM 应返回 TPM_RC_SIGNATURE。
如果密钥在 NULL 层次结构中，则票证中的摘要将是空缓冲区。
注 1 可以在后续命令中使用有效票证向 TPM 提供 TPM 拥有的证明
使用 keyHandle 引用的密钥验证消息上的签名。
如果 keyHandle 引用非对称密钥，则只需要加载密钥的公共部分。
如果 keyHandle 引用对称密钥，则需要加载公共和私有部分。
注 2 要求对称对象的敏感区域允许验证对称签名（HMAC）。

*/
TPM_RC
TPM2_VerifySignature(
    VerifySignature_In      *in,            // IN: input parameter list
    VerifySignature_Out     *out            // OUT: output parameter list
    )
{
    TPM_RC                   result;
    OBJECT                  *signObject = HandleToObject(in->keyHandle);
    TPMI_RH_HIERARCHY        hierarchy;

// Input Validation
    // The object to validate the signature must be a signing key.
    if(!IS_ATTRIBUTE(signObject->publicArea.objectAttributes, TPMA_OBJECT, sign))
        return TPM_RCS_ATTRIBUTES + RC_VerifySignature_keyHandle;

    // Validate Signature.  TPM_RC_SCHEME, TPM_RC_HANDLE or TPM_RC_SIGNATURE
    // error may be returned by CryptCVerifySignatrue()
    result = CryptValidateSignature(in->keyHandle, &in->digest, &in->signature);
    if(result != TPM_RC_SUCCESS)
        return RcSafeAddToResult(result, RC_VerifySignature_signature);

// Command Output

    hierarchy = GetHierarchy(in->keyHandle);
    if(hierarchy == TPM_RH_NULL
       || signObject->publicArea.nameAlg == TPM_ALG_NULL)
    {
        // produce empty ticket if hierarchy is TPM_RH_NULL or nameAlg is
        // TPM_ALG_NULL
        out->validation.tag = TPM_ST_VERIFIED;
        out->validation.hierarchy = TPM_RH_NULL;
        out->validation.digest.t.size = 0;
    }
    else
    {
        // Compute ticket
        TicketComputeVerified(hierarchy, &in->digest, &signObject->name,
                              &out->validation);
    }

    return TPM_RC_SUCCESS;
}

#endif // CC_VerifySignature